1. Field of Invention
This invention relates to suspended flooring used in industrial and manufacturing applications wherein the floor comprises grating support above a base flooring. More specifically, the present invention relates to suspended flooring in cleanroom applications wherein the grating permits airflow through the flooring structure to maintain a cleanroom environment necessary for fabrication of micro chips and other devices requiring a dust-free environment.
2. Prior Art
Current techniques for maintain dust-free environments in clean room structures include the use of a suspended floor structure made up of modular floor gratings which permit airflow therethrough. By providing uniform airflow through the total floor structure, Eddy currents and other non-uniform flow conditions adverse to maintenance of cleanroom environment can be minimized. Airflow introduced from an overhead plenum through a HEPA filter system can be maintained in somewhat laminar flow by virtue of ventilation on a uniform basis through the flooring structure.
Adjustment of flow rate can be partially controlled by introducing dampening structure below each modular grating. Such dampening structure includes an array of slots or openings whose opening sizes are modified by sliding plates or other conventional dampening techniques. Typical dampening structure used with modular grating systems includes sheets or panels with elongated slots which are mounted to the base side of the grating floor members. A series of cover panels are mounted in slidable configuration with respect to the openings or slots. When reduced airflow is desired, the cover panels are slid over the damper openings, thereby restricting airflow. The degree of restriction is proportional to the percent reduction of damper opening size.
A major problem with utilization of dampening structure in connection with floor gratings in cleanroom applications, as well as other industrial applications, arises with collection of spilled chemicals and other material which accumulate on the damper panels and result in corrosive action. For example, inadvertent spilling of acids or other chemicals within the cleanroom result in flow through the floor grating and collection on the damper panels therebelow. If these panels are not immediately removed and cleaned, the collected acids or corrosive materials may have a destructive influence on the damper panels, not only making future adjustment of cover panels along openings more difficult, but also causing actual destruction of the panel structure.
Where cleanroom facilities are in multistory configurations, a more serious risk of injury arises to personnel working in an area under a superior cleanroom structure. In this instance, spilled chemicals may fall through floor grating and contact persons working below. Not only is there concern for injury, but productivity is affected in both levels of cleanroom operations. Some facilities mandate vacating upper cleanroom facilities where persons are working below. Obviously, such problems directly contribute to the high cost of microchip production, requiring that every measure be adopted to avoid suspension of production line activity.
Because cleanroom environments are difficult to maintain and can be compromised by lifting floor members or otherwise disturbing the structural integrity of the room, suspension of production activities for cleaning purposes is often impractical. As a consequence, corrective action with respect to spilled chemicals and corrosive materials must often be delayed until production activities are completed or other opportune cleaning times arise.